Firn found that adding a small amount of fertiliser to affected areas makes the weed tastier to grazing animals, encouraging them focus on the introduced species and thereby taking pressure off native grasses.

Australia spends about A$1.4 billion a year in controlling weeds, yet many continue to spread. The most common methods focus on killing the invaders with herbicides, slashing and bulldozers.

But these techniques can be counterproductive, Firn says. "Trying to get rid of those species with those harsh strategies what we often find is that we end up with another set of weeds coming in or even the same weed species coming back again and again."

Her research aimed to find a smarter solution, one based on figuring out what environmental conditions were favourable to the weeds, and changing them to favour native species.

The problem with African lovegrass is that it grows really well under Australian conditions, Firn explained. "It grows a lot faster than our native grasses, and it is taking over large tracts of land."

"It really is a species that takes advantage of the nutrients that are there, where our native grasses are slower and less responsive to fertiliser. I liken lovegrass to a Corvette driver, and our native grasses are more like Volvo drivers."

Another factor in the weed's dominance is the fact that once it has matured it is tough and unpalatable to grazing animals such as cattle and kangaroos. "So the most effective control measure was to keep grazing but make lovegrass 'tastier' using a low application rate of fertiliser."

In her experiments, Firn found that adding fertiliser did indeed decrease lovegrass abundance and allow native grasses to start to dominate again. "This strategy worked because lovegrass responded very quickly to the added nutrients but grazing pressure kept it from producing seed."

The recommendation from this study is not that fertiliser should be used in all weed scenarios, Firn said.

"We don't recommend that you use fertiliser on all weed species, but that we should understand something about the growth of the weed and what the native grasses need, and change the ecosystem so that it favours the native species again."